Magnetic clutch



Feb. 19, 1929.

J. M. WEYDELL.

MAGNE'PTC CLUTCH Filed June 9, i927 Patented Feb. 19, 1929.

'UNITED STATES 1,702,755 PATENT OFFICE.

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The present invention is in large part an improvement and devolo ment of that set forth in my prior Patent l o. 1,271,401, granted July 2, 1918.

It is the fundamental object of my present invention, as it was thatof such prior patent, to produce an electro-magnetic clutch for c onnecting two moving parts, and to do so without. any sliding contacts and without any moving parts to which outside current must be supplied; that is, to provide an electromagnetic clutch which is energized by a stationary coil.

It is a further object of the present invention to improve the efficiency of such an electro-magnetic clutch, and to simplify its construction; and to provide a clutch in which there is a relative slip between the driving and driven member that for a given magnetization is a direct and smooth function of the load.

The accompanying drawings illustrate my invention: Fig. 1 is an axial section through a magnetic clutch embodying one form of my invention, being taken substantially on the line lil of Fig. 2, and showing diagrammatically the electrical connections; Fig. 2 is a sec-tion on the line 2-2 of Fig. 1; and Figs. 3 and 4 are fragmental sectional views generally corresponding to Figs. 1 and 2, substantially on the lines 3--3 of Fig. 4 and 4-4 of Fig. 3 respectively, but showing a magnetic clutch embodying a somewhat different form of my present inventlon.

Two alined shafts 10 and 11 are mounted in suitable bearings 12 in the stationary frame 13; and are the shafts which are to be drivingly interconnected by the magnetic clutch. The casing 13 is shown as furnishing support 'for the adjacent ends of said two shafts, although such support 1s not essent1al to my invention, as either the shafts or the casing may be the carrier. Further, both the shafts 10 and 11 are shown as solid shafts, rather than as sleeves; but that also is not essential. Either shaft 10 or 11 may be the driving shaft, and either the driven shaft.' Desirably, the abutting ends of the two shafts 10 and 11 have a bearing 12 on each other.

The stationary frame 13 is of suitable nonmagnetic material, such as brass or alum1- num, and supports the magnetizing co1l14of the magnetic clutch; so that such magnet1zing coil is also stationary. The stationary non-magnetic casing carries or has formed 1937. Serial No. 197,867..

as part of it a stationary magnetic Amember 15, which is part of the magnetic circuit. This magneticl member 15 is in the form of a ring lying axially at one end of the stationary coil 14, and desirably has axially extending outer and inner annular flanges 16 and 17 which extend axially partway along the outer and inner surfaces of the coil 14.

The magnetic member 15 is shown asa solid member, as it is ordinarily unnecessary to laminate it; but my invention does not preclude having such member laminated. The connection Wires 18 for the magnetizing coil 14 may pass through suitable openings in the magnetic member 15 and non-magnetic casmg 13 for suitable connection to a source of current such as a battery 19, and to a suitable controlling device such as a rheostat 2O by which the circuit of the magnetizin coil may be made and broken and by which esirably the strength of magnetization may be varied.

The shaft 10. has fixed thereto ama eticmater1al member 21, shown as Solid tlbugh not necessarlly so especially in the larger machines, which is located within the opening in the coil 14 and stationary magnetic member 15, and fits fairly closely within the inner annular flange 17 with just sufficient clearance for free operation, so that the air gap will be small. The rotatable magnetic member 21 has an outwardly extending flange 22 at its axial end remote from the stationary magnetic member 15, so that the stationary coil 14 lies axially between such rotating flange 22 and the stationary magnetic member 15. .At its outer periphery, the flange 22 is provided with a series of radially outwardly projecting fingers 23, which constitute denite polar projections, all of the same polarity. The drawing shows eight such polar projections 23; but that number is a mere incident, as any desirable number of such polar projections may be used.

In addition to the inner magnetic-material member 2l, which lies within the coil 14, the shaft 10 also carries an outer magnetic-material member 31; which lies circumferentially outside of the magnetizing coil 14 and stationary magnetic member 15 and fits fairly closely around the outer annular flange 16 with just sufficient clearance forfree operation, so that the air gap will be small. This outer rotatablemagnetic member 31 is carried from the inner rotatable magnetic member 21 by a carrying memben`32 of non-magnetic material; so that the two members 31 and 21 are not magneticall contiguous. As

shown, both magnetic mem ers 21 and 31 are fastened to the non-magnetic ring 32 by suitable attaching screws. The outer magnetic member 31 at its axial end remote from the polarity, alternate circumferentially, as' is clear from Figs. 2 and 4, and are in fixed relation to one another. This circumferential alternation of the poles of opposite polarity is one of the important features of the present invention; and is a feature of both modiiications shown, as illustrated in Figs. land 2, and Figs. 3 and 4, respectively.

The two illustrated embodiments of the invention differ from each other, however, in that in the embodiment shown in Figs. 1 and 2 the polar projections 23 actually project radially outward between the polarprojections 33, as is clear from Fie'. 2, whereas in the embodiment shown in Figs'. 3 and 4 the outer ends of the radial rojections 23 lie radially inwardly of the ra ially inward faces of the projections 33 to provide a free annular space 34, the purpose of which will be described later.

The shaft 10 with the parts 21, 22, 23, 31, 32, and 33 constitutes one of the two clutch members between which the clutch is to transmit the ower; and by reason of the magnetization produced by the stationary coil 14, there exists in connection with this clutch member a magnetic ieldbetween the polar projections 23 and the polar projections 33which polar rojections are alternately of opposite polarity around the circumference of said rotatable member. This magnetic field rotates with the shaft 10, at the same speed.

The other clutch member comprises the shaft 11, a carrying disk 4() of non-magnetic material fixed on said shaft to rotate therewith, and a rotor member carried by and rotatable with said carrying disk 40 and .located in the iield between the polar projections 23 and the polar projections 33. This rotor member is arranged to have currents induced in it by its relative movement in the aforesaid magnetic field, the production of which induced currents consumes energy, and thus creates a drag'between said rotor member and the rotating field from the polar proj ections 23 and 33, tending to make said polar projections and said rotor member (and therefore the two shafts 10 and 11) rotate together, with a relative slip between them dependent upon the load transmitted and on polesv 23^and 33, and surrounds the entire ,circumferential series of such poles 23 and 33. In the arrangement shown in Figs. 3 and 4, the rotor member lies in the annular "space 34 above referred to, thus being radially outside of the circumferential poles 23 and 'radially inside of the circumferential poles 33.

The two forms will be explained separately.

In the arrangement shown in Figs. 1 and 2, the rotor member is desirably in effect a squirrel-cage rotor. It comprises a series of annular laminas 41 clamped between the carrying disk 40 on one side and an endconnection ring 42 on the other side by rivets 43 which serve both as clamping rivets and as squirrel-cage bars for carrying the induced currents. The lamin 41 surround the circumferential series of poles 23 and 33, with a suflicient air gap between for mechanical clearance; and serve to carry the magnetic lines of force between the poles 23 of one clarity and the poles 33 of theother polarity.

pon relative rotation between the poles 23 and 33 on the one hand and the laminas 41 on the other hand, the cross-connectors 43 cut the magnetic lines of force, so that currents are induced in such crossfconnectors. Such cutting of the lines of force by the crossconnectors is in op o'site directions over the 'poles 23 and over t e poles 33, so that some of the cross-connectors develop differences of potential tending to create current How from the disk 40 to the ring 42 wlile others develop differences of potential tending to create current lowin the opposite direction. Such current ilow occurs, as the circuit'is complete from one cross-connector to another through the carrying disk 40 and the connection ring y 42 in the same manner as in a squirrel-cage rotor.

For greater effectiveness in this generation of induced currents, the rivets constituting the cross-connectors of the squirrel-cage rotor are desirably located fairly close to the inner edges of the laminae 41; and desirabl the holes in which such rivets lie commun1 cate with radial slots 44 extending inward to the inner edges of the laminae to provide open slots, as it were, to compel the lines ofv force generally to pass radially outward in the laminae beyond the rivets 43, so that the reater part of such lines of force may be eut y the rivets 43 upon relative rotation between the magnetic field to the poles 23 and 33 and the rotor 4Q-41-42-43.

Although I prefer a rotor member of the squirrel-cave type when such rotor member lies radially on the same side of both sets of poles 23 and 33, as is illustrated in Figs. l and 2, yet my invention does not preclude other forms of induction-motor rotors in tlicat location.

In the arrangement shown in Fi s. 3 and 4, the rotor member lies in the annu ar space 34, radially between the circumferential series of poles 23 of one polarity and tlie circumferential series of poles 33 of the other clarity. Any type of induction rotor may Ee used here, but t e simplest type is a simple ring 50 of iron, which serves to carry ,the

'magnetic lines of force between the poles 23'of one polarity inside of it and the pole 33 of the other polarity outside of it.

Upon relative rotation between the iron rin 50 and the field between the poles 23 an 33, the magnetic field travels circumferentially in the iron ring 50, and develops eddy currents which tend to oppose such relative rotation. This produces a drag b etween the 4two members of t-lie clutch, tending to make the two shafts l0 and 11 rotate together, with a slip dependent upon the load transmitted and u on the strength of the Y field produced by t 'e stationary coil 14.

I claim as my invention: 1. A magnetic clutch, comprising a rotary member having two magnetically separate lmagnetic portions, each of said magnetic portions having polar projections which are spaced from the polar projections of the other magnetic portion, all of said polar projections lying substantially in the same plane and the polar projections of one magnetic portion being angularly displacedr from those of the other magnetic portion, a second rotary member having thereon an induction-inotor rotor in inductive relation to said olar projections, a stationary magnetic member in close proximity to and magnetically between the two magnetic portions of said first rotary member, and a stationary magnetizing coil iii magnetizing relation to said stationary magnetic member and to the nagnetic portions of said first rotary mem- 2. A magnetic clutch, comprising a rotary member having two magnetically separate magnetic portions. each of said magnetic portions having polar projections which are spaced from the polar projections of the other magnetic portion, the polar projections of one magnetic portion being angularly displaced from those of the other magnetic por tion, a second rotarv member having thereon an induction-motor rotor in inductive relation to said polar projections, a stationary magnetic member in close proximity to and` magnetically between the two magnetic portions of said first rotary member, and a stationary magnetizing coil in magnetizing relation to said stationary magneticmember lon an induction-motor rotor in inductiverelation to said olar projections, a stationary magnetic mem er in close proximity to and magnetically between the two magnetic portiona magnetizing coil in magnetizing relation \o said stationary-magnetic member andv to the magnetic portions of said first rotary member.

4. A magnetic clutch, comprising a rotary member having two ma etically separate magnetic portions, each o said magnetic poi'- tions having polar projections which are spaced fr' m the polar projections of the other magnetici portion, a second rotary member having thereon an induction-motor rotor in inductive relation to-said polar projections, a stationary magnetic member in close proximity to and magnetically between the two magnetic portions of said first rotary member, and a stationary magnetizing coil in magnetizing relation to said stationary magnetic member and to the magnetic portions of said first rotary member.

5. A magnetic clutch, comprising a rotary member having two magnetically separate magnetic portions, each of said magnetic portions having polar projections which are spaced from the polar projections of the other magnetic portion, a second rotary member having thereon an induction-motor rotor in inductive relation to said polar projections, a stationary magnetic member in close proximity to and magnetically between the two magnetic portions of said first rotary member, and a stationary magnetizing coil in magnetizing relation to said stationary magnetic member and to the magnetic portions of said -tionox said first rotary member, and a sta.-

first rotary member, said induction-motor r'otor being of the squirrel-cage type.

6. A magnetic clutch, comprising a rotary member having two magnetically separate magnetic portions, each of said magnetic portions having polar projections which are spaced from the polar projections of the other magnetic portion, a second rotary member having thereon an induction-motor rotor in inductive relation to said polar projections, a stationary magnetic member in close proximity to and magnetically between the two magnetic portions of said first rotary member, and a stationary magnetizing coil in magnetizing relation to said stationary magnetic member and to the magnetic portions of said first rotary member, said induction-motor rotor lying circumferentially outside of both sets of polar projections.

- 7. A. magnetic clutch, comprising a rotary member having twov mafgnetically separate magnetic portions, each o said magnetic portions having polar projections which are spaced from the polar projections of the other magnetic portion, a second rotary member having thereon an induction-motor rotor in inductive relation to said polar projections, a stationaiy magnetic member in close proximity to an magnetically between the two magnetic portions of said first rotary member, a

stationary magnetizing coil in magnetizing relation to said stationary magnetic memberand to the magnetic portions of'said first rotary memberthe two sets of polar projections lying in the same circle with the lar plrijections of one set angularly disp aced m those of the other set, and the inductionmotor rotor being in an outer circle surrounding the circle of the polar projections.

8. A magnetic clutch, comprising a-stationary magnetic member, a stationary magnetizing coil in magnetizing relation thereto, a r0- tary member having an'inner magnetic portion surrounded by and a magnetically separate outer magnetic portion surrounding said stationary magnetizing coil, said stationary magnetic member being in proximity to and magnetically between said two etic portions of said rotary membeijan said two magnetic portions of said rotary member having olar projections andl a second rotary mem r having an induced-current magnetic member in magnetic proximity to both sets of polar projections ofsaid first rotary member. 9. A magnetic clutch, comprising a stationary magnetic member, a stationary magnetizing coil in ma etizing relation thereto, a rotary member aving an inner magnetic portion surrounded by anda magnetically separate outer magnetic portion surrounding said stationary magnetizing coil, said stationary magnetic member being in proximity to and magnetically between said two ma J ARL M. WEYDELL.

etic portions of said rotary member, an said twov 

